Introduction to the 990-08-70-03-00 Vibration Transmitter
When you need dependable vibration monitoring for rotating machinery, the 990-08-70-03-00 from Bently Nevada delivers precise, loop-powered signal conversion. This 990 Vibration Transmitter accepts one non-contacting 3300 NSv proximity probe and extension cable, making it a straightforward choice for integrating into existing monitoring systems. Its full-scale range of 0-8 mils pp (0-200 μm pp) suits applications where shaft vibration must be tracked accurately.
Engineered for industrial environments, the transmitter operates on +12 to +35 Vdc input at the terminal, with a maximum loop resistance of 1,000 Ω including cable at 35 Vdc. The 4-20 mA output provides a standardized signal for PLCs, DCSs, or standalone indicators. With a system length of 7.0 meters (23.0 feet), this model supports flexible installation layouts.
Key Features and Technical Specifications
The 990-08-70-03-00 stands out for its robust performance and ease of use. Here are the critical specifications you can rely on:
- Input: Accepts 1 non-contacting 3300 NSv proximity probe and extension cable.
- Power: Requires +12 to +35 Vdc input at the transmitter terminal.
- Signal Output: 4 to 20 mAdc over specified full-scale range in 2-wire configuration.
- Loop Accuracy: Within ±1.5% over specified full-scale range (from TEST signal input to voltage across 250 Ω loop resistance).
- Probe Gap: Must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from target to ensure full-scale range.
- Maximum Loop Resistance: 1,000 Ω including cable at 35 Vdc.
- Current Limiting: 23 mA typical.
- Zero and Span: Non-interacting external adjustments.
- NOT OK/Signal Defeat: Output goes to less than 3.6 mA within 100 µs after a Not OK condition; restored within 2-3 seconds after removal.
- Frequency Response: 5 Hz to 6,000 Hz +0, 3 dB.
- Minimum Target Size: 9.5 mm (0.375 in) diameter.
- Leadwire Length: Maximum for Proximitor Sensor Output (BNC connector) is 3 meters (10 feet).
- Hazardous Area: Suitable for Non-Hazardous, Zone 2, or Div 2 locations with a 28 V power supply.
One distinctive aspect is the fast NOT OK response—the signal drops below 3.6 mA within 100 µs, enabling rapid fault detection. This feature is critical for protecting machinery from undetected vibration anomalies.
Applications and Use Cases
The 990-08-70-03-00 is ideal for monitoring shaft vibration in pumps, motors, fans, and compressors. Its 4-20 mA output integrates easily with existing control systems, allowing continuous trend monitoring. For example, in a petrochemical plant, this transmitter can feed vibration data to a DCS, triggering alarms before damage occurs. Additionally, its compact DIN clip mounting simplifies retrofits in crowded panels.
Installation and Setup
Proper installation ensures accurate readings. Mount the transmitter using the provided DIN clips and screws (Mounting Option 03). Connect the 3300 NSv probe and extension cable to the input. Ensure the probe gap is set between 0.5 and 1.75 mm (20 to 55 mils) from the target—this is essential for full-scale range. Wire the loop with a power supply of +12 to +35 Vdc, keeping total loop resistance below 1,000 Ω at 35 Vdc. Use shielded cable for the BNC output, with a maximum length of 3 meters (10 feet).
Maintenance and Reliability
Routine inspection of the probe gap and cable connections is recommended to maintain accuracy. The transmitter's non-interacting zero and span adjustments simplify calibration. Since the unit is designed for continuous operation, periodic verification of the 4-20 mA output against a known vibration level helps detect drift. Always follow the manufacturer's manual for detailed maintenance procedures.
Compatibility and Integration
This transmitter is designed to work with Bently Nevada 3300 NSv proximity probes. Its 2-wire 4-20 mA output is universally compatible with most PLCs, DCSs, and SCADA systems. The DIN clip mounting allows easy installation in standard industrial enclosures. For hazardous area installations, ensure the power supply is limited to 28 V as specified.
Product Support and Availability
The 990-08-70-03-00 is available through AutoDCSTech. Contact our team to confirm current stock and lead times. We are ready to assist with your industrial automation needs.
